Starbucks hasn't had a lot of good PR recently, but this latest stunt takes the biscotti.

A big screen at one of the coffee chains pop-up-cafe's saw tweets with the hashtag 'spread the cheer' pulled in automatically after the moderating facility went awry.

Brewed awakening

News spread quickly over the microblogging site that the big screen was flagging up hate tweets over the Natural History Museum's ice rink, only encouraging Twitter users to venti their rage.

Kate Talbot who took the photos of the tweets at the ice skating rink told the Huffington Post UK she posted it on Twitter, where it was shared thousands of times.

"It was obviously supposed to be a friendly interactive publicity thing," she said, "but well over half the tweets were about how mean they were to their staff/how little tax they'd paid, so I took a few pictures.

"One of the tweets is about tipping the staff as apparently Starbucks just cut their wages, two of them are the picture I originally tweeted, but possibly my favourite is the one at the bottom - the screen then started showing RTs of my original tweet!"

A lot of the tweets were embarrassing for the coffee chain

After it emerged the coffee chain paid less than 1% in corporation tax over 14 years, Starbucks has their beverages boycotted, their branches besieged and has been forced to cough up £20m in corporation tax over the next two years.

A four-month investigation by news agency Reuters discovered that Starbucks was able to cut income tax by paying fees to other parts of its global business, such as royalty payments for use of the brand.

This means Starbucks UK is effectively making a loss and therefore does not have to pay any corporation tax. As a result, it has not broken any law.

The most recent results, posted for 2011, show Starbucks UK recorded a loss of £33 million.

A spokesperson for the Natural History Museum said in a statement that sponsorship by Starbucks helped the museum to continue offering activities and providing exciting displays.

They apologised for the boob, saying the offensive comments had now been removed. The museum explained: "The moderation filter for the twitter wall screen crashed, leading to two comments being displayed about ice rink sponsor Starbucks that included swear words.

"The Museum apologises to anyone who may have been offended by messages displayed on the Starbucks twitter wall screen in our ice rink café containing inappropriate language. The offensive comments have been removed from display."

A Starbucks spokesperson said:“We apologise to any visitors who may have been offended by inappropriate messages displayed on the Twitter wall screen at the Natural History Museum’s ice rink café on Sunday. This was due to a temporary malfunction with the content filtering system.

"As a family-friendly, responsible company we are committed to ensuring that our publicly displayed content is appropriate for all audiences and profanity filters have been in constant operation since the ice rink opened in November.”